exceptional-run.raku

use v6;


BEGIN { 
    class X::Shell::CommandNotFound is Exception {
        has $.cmd;
        method message { 'The shell command ⟨' ~ $.cmd ~ '⟩ was not found.' }
    }
    class X::Shell::NoAccess is Exception {
        has $.cmd;
        method message { 'The shell command ⟨' ~ $.cmd ~ '⟩ is not accessible.' }
    }

    package Shell {}

    sub shell-command(IO() $cmd-path) {
        my $cmd-name = $cmd-path.basename;

        X::Shell::CommandNotFound.new(:cmd($cmd-name)).throw if !$cmd-path.e;
        X::Shell::NoAccess.new(:cmd($cmd-name)).throw if !$cmd-path.x;

        my $Exception = Metamodel::ClassHOW.new_type(:name($cmd-name));
        $Exception.HOW.add_parent($Exception, Exception);
        $Exception.HOW.add_attribute($Exception, Attribute.new(:name<$.exitcode>, :type(Int), :package($Exception), :has_accessor));
        $Exception.HOW.add_attribute($Exception, Attribute.new(:name<$.stderr>, :type(Str), :package($Exception), :has_accessor));

        $Exception.HOW.add_method($Exception, 'message', my method { 'Shell command ⟨' ~ self.^name ~ '⟩ finished with non-zero exitcode of ' ~ self.exitcode ~ '.' } );

        $Exception.HOW.compose($Exception);

        X::Shell::<ls> := $Exception;
        Shell::«$cmd-name» := sub (|c) { 
            my $proc = run $cmd-name, |c, :out, :err; 
            if $proc.exitcode != 0 { # this makes the exception resumeable
                my $e = X::Shell::«$cmd-name»;
                $e.new(:exitcode($proc.exitcode), :stderr($proc.err.slurp)).throw
            } else {
                $proc.out.slurp
            }
        }
    }

    my \e = shell-command('/bin/ls');
}

Shell::ls('/home/not there', '-l');
Shell::ls('/home/dex').lines.tail(10).say;

CATCH { 
    when X::Shell::ls { warn .stderr, .backtrace; .resume }
    when X::Shell { warn .^name, ': ', .message; .resume } 
}

# say $e.^attributes;
# dd $e.new(:exitcode(1)).message;